According to the purity of the antahkarana (the ‘inner instrument’ or ‘inner organ’, the various functions of which are classified in four divisions, manas (mind), buddhi (intellect), chitta (will) and ahamkara (ego)) the same teaching reflects in different ways in different people.
There are various stories in the Upanishads and Puranas that illustrate that according to the purity of the antahkarana the same teaching reflects in different ways.
One such story is as follows: Indra and a rakshasa (demon)
both received the teaching ‘tat tvam asi’ (that you are) from a guru. The rakshasa
understood this to mean that his body is ‘that’ (brahman, the ultimate reality),
so he began to do tapas to make his body immortal and to gain power and
pleasures for himself. Indra, however, carefully considered the meaning of this
teaching for one hundred years, and finally concluded that his body could not
be brahman, so he returned to the guru and asked whether his prana (life) could
be brahman, to which the guru replied: ‘No, you are not the prana; you are
that’. After another hundred years of manana (deep and careful consideration) he
decided that perhaps his mind is brahman, but when he asked the guru, he was
told: ‘No, you are not the mind; you are that’. After a further hundred years
of manana he decided that perhaps his intellect is brahman, but the guru told
him: ‘No, you are not the intellect; you are that’. After yet another hundred
years of manana he decided that the anandamaya kosha (the will, which consists
of vasanas) must be brahman, but the guru said: ‘No, you are not the anandamaya
kosha; you are that’. After carefully considering this, he understood that he is
the awareness in which all these five sheaths appear and disappear, so he
turned his attention back within to investigate awareness itself, and thereby
he merged forever in that, as that.
Since the mind of the rakshasa was very impure, he did not
pause to think carefully about the teaching he was given, so he hastily concluded
that his body is brahman. In other words, he stopped at the stage of shravana (hearing
the teaching) and did not go on to do manana, so he failed to understand the
deep import of the teaching.
Indra’s mind, on the other hand, was purer, so he did not
jump to any hasty conclusion, but carefully considered what the teaching actually
meant, and as a result of his careful and patient manana his mind was further
purified, so he eventually understood the correct meaning and practical
implication of the teaching, and hence he did nididhyasana (deep contemplation),
turning his attention back within to investigate and know who am I.
From beginning to end, the teaching of the guru remained the
same: ‘tat tvam asi’. However, because of his dedicated manana Indra’s mind was
progressively purified by meditating on the words of his guru, so he steadily
came closer to understanding the correct import and practical implication of
the teaching.